Generally, glass flakes widely are used for applications such as a reinforcing material for thermosetting resin or thermoplastic resin, and a filler for corrosion-resistant lining.
JP 62 (1987)-109855 describes a technique for enhancing the strength and dimensional stability of a thermoplastic resin by mixing glass flakes into the thermoplastic resin. JP 63 (1988)-225554 A, JP 3 (1991)-86753 A, JP 5(1993)-287175 A, JP 2002-212421 A, and JP 2003-82260 A describe that flaky-glass granules formed using a binder and/or a surface treatment agent are mixed into a thermoplastic resin.
Since the glass flakes are scaly thin pieces, there has been a problem in that they have a high scattering property and they have poor workability before being mixed into the thermoplastic resin. Usually, an extruder is used when mixing glass flakes into a thermoplastic resin. However, since glass flakes are bulky and have a poor fluidity, there has been a problem of the glass flakes clogging a feeder and the mixability of the glass flakes into the thermoplastic resin is poor. In order to solve these problems, there has been developed a technique in which glass flakes are granulated using a binder and/or a surface treatment agent to form granules, and then the granules are mixed into a thermoplastic resin.
However, in the case where the flaky-glass granules formed using a binder and/or a surface treatment agent are mixed into a thermoplastic resin, a problem occurs occasionally in that when the thermoplastic resin is molded at a high temperature, the binder and/or the surface treatment agent is decomposed thermally and gas is generated, causing foam inclusion and discoloration in a molded article of the resin.